Sanding disk



y 1957 H. 0. SHORT 2,800,752

SANDING DISK Filed April 11, 1956 v INVENTOR. HAROLD 0. SHORT BY 511.; A BMLxg SL4, m ia ilnited States Patent SANDIN G 'DISK Harold 0. Short, Towson, Md., assignor to The Black &

Decker Manufacturing Company, Towson, Md., a corporation of Maryland Application April 11, 1956, Serial No. 577,590

3 Claims. (Cl. 51-197) This invention is directed to improvements in disk type mounting pads for abrasive disks and more particularly to the type known as feather edgers.

Such abrasive disk carriers are usually formed of a cushioning material such as pliant rubber or the like carried on a stifier rubber backing cured or cemented to a hub structure attachable to the propelling means. The abrasive disk usually is held upon the flexible backing by a clamping disk which is disposed below the plane of rotation of the abrasive disk. Various clamping means have been proposed since such clamping means can involve the element of danger to the operator if of improper construction.

The general object of the present invention is the provision of a novel abrasive disk clamping means which cannot be released during the use of the apparatus but which is quickly removable while being secured against release while the apparatus is in use.

A more specific object of the present invention is the provision of an abrasive disk clamping means on a feather edger which will hold the abrasive disk out of the plane of rotation of the disk i. e. at its central region suificiently firmly as to prevent slippage between the abrasive disk and the backing structure regardless of the amount of distortion exerted upon the abrasive disk and backing structure.

A still further object of this invention is the provision of a quick release abrasive disk clamping means.

Other objects of the present invention will become apparent to those skilled in the art from the following description referring to the accompanying drawings showing a preferred embodiment thereof. The essential characteristics are summarized in the claims.

In the drawings:

Fig. 1 is a cross sectional view taken through the axis of the disk mounting head showing the abrasive disk locking mechanism in locked position; and

Fig. 2 is an end view of a cam member comprising part of the disk locking means.

Referring to the drawings in Fig. 1 I show a yieldable rubber backing member 12 which is cured or cemented to an internally threaded hub structure 13 having an integral disk formation 14 about which the backing 12 is molded and secured. The backing 12 has a pliable cushion 15 secured thereto and having a coniform depression 16 at its central region. The abrasive disk 15 is depressed into this coniform depression and clamped to the rubber cushion as will be explained.

The abrasive disk locking means comprises a cup shaped and flanged member 18 the outer flange 18a of which serves to depress the central region of the abrasive disk 19 and clamp it to the pad 15.

The cup shaped member 18 has a perforated bottom for the passage therethrough of a headed locking bolt 20 and a compression spring 34 thrusting against the bottom of the cup formation and the head 35 of the bolt tends at all times to urge the bolt outwardly to release the abrasive disk.

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The bolt 20 has an inner pilot end 21 for camming the inner end of a detent plunger 22 radially outwardly against the influence of a ring spring 23 which has one end 24 bent radially inwardly to fit in a radial bore formed in the hub structure as shown in Fig. 1. The inner end of the plunger 22 snaps behind a detent shoulder 25 formed as shown adjacent the domed pilot end 21 of the inner end of the bolt.

To retract the plunger v22 to release the bolt a ball 26 is carried by the plunger to engage in a cam cavity 32 formed in a radial face of a manually turnable downwardly flanged or skirted disk member 30 mounted on the exterior of the hub structure and which is held in axial position by a spring washer 31. When the member 30 is turned manually to cam the ball 26 and plunger 22 outwardly against the bias of spring 23, a spring 34 disposed between the bottom of the cup 18 and bolt head 35 will cause the cup to pop outwardly and release the abrasive disk.

It will be noted that the manually operated member 30 is of a cap shape to shroud the ring spring 23 and detent plunger 22. Also it will be noted that the inclination of the cam formation 32 is not steep so that the member 30, ball 26 and plunger will stay locked relative to the bolt during use of the apparatus. Preferably the cam slot direction of inclination is chosen relative to the contemplated rotational drive of the disk, so that rotation of member 30 relative to the hub, due to starting inertia, and thereby any tendency toward clamp release is prevented.

In applying an abrasive disk to the pad, the disk is slipped over the bolt and cup and the bolt head is pressed inwardly until the inner end of the plunger snaps behind shoulder 25, torsional components being developed through ball 26 on cam surface 32 upon outward movement of pin 22 to displace cam member 30 rotationally in one sense and upon the biasing action of spring 23 moving the pin inwardly to return cam member 30 to locked position. Thus the ring spring 23 is to be of sufiicient strength to attain such motions as well as to hold the plunger 22 in its innermost position against the influence of centrifugal force. Accordingly hand manipulation of the cap member 30 is required only to retract the plunger and release the bolt.

I claim:

1. A support and driving means for an abrasive disk comprising a hub structure adapted to be attached to a driving spindle, an abrasive disk back up structure comprising a rubber back secured to the hub structure, a flanged cup shaped member, a helical spring in the cup of said member, a securing bolt urged outwardly by the spring while the spring exerts inward pressure on the flanged cup shaped member, a radially shiftable means carried by the hub structure at the rear of said rubber back including a plunger and a spring carried by the hub structure and bearing upon said plunger to maintain the plunger in detent engagement with the bolt and a manually settable disk on the rear of the hub structure con nected for operating said radially shiftable means in an outward direction to release the bolt.

2. A support and driving means for an abrasive disk comprising a hollow hub structure adapted to be attached to a driving spindle, an abrasive disk back up structure comprising a rubber back secured to the hub structure, a flanged cup shaped member adapted to clamp an abrasive disk to the back up structure, a helical spring in the cup of said flanged member, a securing bolt urged outwardly by the spring while the spring exerts inward pressure on the flanged cup shaped member, an inwardly urged radially disposed detent plunger carried by the hub structure at the rear of said rubber back to maintain the plunger in detent engagement with the bolt and a manually settable disk on the rear of the hub structure, said settable disk being cam connected to the plunger by a ball member permitting of unlocking the plunger in an outward position.

3. A support and driving means foran abrasive disk comprising a hub structure adapted to be attached'to a driving spindle, an abrasive disk back up structure comprising a rubber back secured to the hub structure, a flanged cup shaped member, a helical spring in the cup of said member, a securing bolt urged outwardly by the spring while the spring exerts inward pressure on the flanged cup shaped member, a radially disposed detent plunger carried by the hub structure at the rear of said rubber back and a ring spring carried by the hub structure and bearing upon said plunger to maintain the plunger in detent engagement with the bolt and a manually settable disk on the rear of the hub structure connected to the plunger by means permitting of unlocking of the plunger in an outward direction against the influence of said ring spring.

References Cited in the file of this patent UNITED STATES PATENTS 

